1. Field of the Invention
This invention relates to knee braces, and more particularly to an improved knee brace for supporting the knee to prevent certain motion of the knee joint that could injure the ligaments of the knee, while allowing the knee joint to otherwise bend safely about a horizontal axis through the knee.
2. Description of the Prior Art
A knee brace can be worn by a post-operative patient who has had knee surgery. Knee braces also are worn by persons who suffer knee instabilities and by other persons engaged in sporting activities to prevent sporting injuries to the knee. The common purpose of a knee brace is to provide exterior support for the knee to prevent any unnatural movements of the knee joint which could injure or re-injure the knee ligaments, while allowing the normal swinging movement of the knee joint about a horizontal axis through the knee (viz., forward and backward movement of the lower leg or tibia relative to the upper leg or femur, as in a normal walking motion). One type of motion to be prevented by a knee brace is a sudden movement of the upper and lower legs to one side or the other. Another type of motion to be restrained is a twisting or rotation of the lower leg relative to the upper leg about a vertical axis.
A prior art knee brace for supporting the knee in the manner described above is disclosed in U.S. Pat. No. 3,669,105 to Castiglia. The knee brace disclosed in that patent has a pair of lateral uprights extending along the outside of the leg and articulated at the outside of the knee joint by a single axis pivot pin. Upper and lower contact pads attached to the ends of the uprights contact the outside of the thigh and lower leg above and below the knee joint. Curved, rigid bars extend from the upper and lower contact pads around and in front of the upper and lower leg to the inside of the knee joint where the ends of the bars are interconnected by another single axis pivot pin. A condyle pad attached to the inside pivot pin engages the inside of the patient's knee joint. The pad rotates about the pivot pin axis independently of the upper and lower curved bars. A pair of wide elastic rubber straps attached to the upper and lower contact pads are used to encircle the leg above and below the knee joint to support the curved bars on the upper leg and lower leg. A smaller elastic strap is attached to the lower contact pad and is spiraled upwardly around the back of the knee and attaches to the upper contact pad. This strap is intended to provide a de-rotation capability preventing the lower leg from rotating or twisting relative to the upper leg about a vertical axis.
The knee brace in the Castiglia patent suffers from a number of shortcomings which are overcome by the present invention. For example, the curved bars supported on the front of the tibia and the femur can be discomforting to the patient, particularly the lower curved bar that can cause pressure over the crest of the tibia. The present invention provides a knee brace which is more comfortable, in part, because it eliminates pressure points at the front of the legs. In addition, the knee brace of this invention provides better overall contact with the sides of the knee joint, by providing a pair of floating condyle pads with a unique hinge arrangement that applies spring biased pressure that maintains total contact between the condyle pads and the knee joint through the full range of motion at the knee. Further, an improved de-rotation arrangement is provided that is less cumbersome and more effective in preventing undesired twisting of the lower leg relative to the upper leg.